Study: Fish Oil Supplements Don't Prevent Heart Attacks

Taking fish oil pills rich in omega-3 fatty acids doesn't appear to have a significant effect on heart attacks, strokes or death, a study published today in The Journal of the American Medical Association finds.

The news comes even as sales of fish oil supplements are booming. In 2011 Americans spent $1.1 billion on them, up 5.4% from 2010, according to the Nutrition Business Journal.

The researchers reviewed 20 well-designed clinical trials that looked at the health outcomes of people taking omega-3 polyunsaturated fatty acid supplements derived from fish oils. The trials dated from 1989 to 2012 and included 68,680 people who were studied for at least a year. They found no statistically significant association between all deaths, cardiac-related deaths, sudden deaths, heart attacks and strokes among people taking the supplements.

The review was led by Evangelos Rizos, a professor of medicine at the University Hospital of Ioannina in Greece.

The medical world long ago noted that societies in which diets were high in fatty fish such as salmon, sardines, mackerel and others had lower rates of heart disease. A large 1989 study found that men who had already had a heart attack and changed their diets to include more fatty fish rich in omega-3 polyunsaturated fatty acid were 29% less likely to die in the next two years. Because of these and other findings, many medical groups suggest that people at risk for heart disease either increase their fatty fish intake or take omega-3 supplements.

However, subsequent studies that looked at omega-3 fatty acid supplements derived from fish were less clear. Some supported and some refuted the findings, though overall the connection between supplements and lowered heart disease has been elusive. The study released today attempts to pull together all the current research.

The message Americans may not want to hear is that eating healthy foods, not taking pills, is what helps heart health, says Richard Karas, director of the preventive cardiology center at Tufts Medical Center in Boston.

Time and time again research shows that a diet rich in a certain vitamin or nutrient is beneficial. But then people think "if you take a pill containing that ingredient, you'll be healthier," Karas says. It doesn't work that way.

He now tells his cardiac patients to eat fatty fish in at least two meals a week.

Duffy MacKay, vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, a supplement industry group, disputed the findings. He noted that many of the studies in the JAMA review were on people who were already sick and so might not apply to maintaining health.

Many of the studies also didn't test to see whether people were starting out with diets very low in fatty fish and therefore omega-3s. Americans know they should be eating a diet high in fatty fish, he says. But "the reality is that people are simply not doing this. Omega-3 supplements serve as an affordable, convenient and safe way to obtain omega-3 fatty acids and the array of health benefits they offer."

Karas says the good news is that there's apparently no danger to taking fish oil supplements. "But they may or may not be providing the benefit people had originally hoped for."

No one knows exactly why eating lots of omega-3 fatty acids appears to be good for health. It's been suggested, but not proved, that they might lower triglyceride levels.

However, the U.S. Food and Drug Administration has approved their use only to lower triglycerides in patients with pancreatitis, a disease of the pancreas.

The researchers cautioned that while their findings didn't justify the use of omega-3 in general, more research is needed to look at whether it might be useful for specific patient populations or illnesses.